Project 1

Therory

You can model the mechanical part of the system in Simscape Multibody. For example, to model the cylinder and piston, you can use the Revolved Solid (Simscape Multibody) and Cylindrical Solid (Simscape Multibody) blocks. To provide the translational degree of freedom for the piston, use a Prismatic Joint (Simscape Multibody) block. To easily calculate the lengths of the chambers A and B, you can attach the base frame (B) and follower frame (F) of the joint to the centers of the left inner surface of the chamber A and the left surface of the piston, respectively. Make sure that the Z-axes of the B and F frames are aligned and both point toward chamber B.

Using this convention, the length of the chamber A, dA, is the position output of the joint block, and the length of the chamber B, dB, equals the difference of the stroke length and dA. To ensure that the piston does not travel beyond the ends of the cylinder, you can specify the upper and lower position limits of the Prismatic Joint block.

In chamber A, a pressure at port A moves the piston from 0 to stroke length. The displacement of the piston equals to the position output of the Prismatic Joint block. To model chamber A:

In chamber B, the pressure at port A moves the piston from 0 to negative stroke length. Therefore, you need to change the default orientation and add an offset to the input position signal of the lower Translational Mechanical Converter (IL) block. The offset equals -dB.

To limit the travel of the piston:

Double-acting cylinder systems can be used in many applications. For example, a dump trailer can use a double-acting cylinder to actuate a scissor hoist mechanism that raises and lowers the dump bed. See Hydraulic Interface - Dump Trailer with Hydraulic Cylinder (Simscape Multibody) for more details. Under the mask of the Double-Acting Hydraulic Cylinder block in the scissor hoist are the mechanical and hydraulic subsystems, which are connected by a Translational Multibody Interface block. The Prismatic Joint block in the mechanical subsystem provides the position information to the two actuators in the hydraulic subsystem, Head Chamber and Bottom Chamber, that have the opposite settings of the Mechanical orientation parameter. The Constant block C provides a position signal offset to the Head Chamber actuator, because when the Bottom Chamber is at dead volume (where position p = 0), the Head Chamber is at maximum stroke.

MODEL

mechanical system

physical system

The hydraulic oil is suppied by the source. The hydraulic oil is passed to a 4 way valve which changes the position according to the input given. Here we are using a signal builder to provide input. The A side of the valve is connected to the chamber A and the B side is connected to the chamber B. The A and B chambers acts in opposite direction. The output of the camber is provided to the translational multibody interface which produces a force based on the movement.

The force is then transferd to prismatic joint as input. The prismatic joint moves accourding to the input provided and a actuation is created on the multibody side. The multibody consist of a cylindical solid for piston side and a cylindrical and two revolute solid for cylinder side.

A solver configuration , mechanism configuration and world frame is attached to the model.

Multibody

cylinder head

body

bottom

piston head

piston rod

parameters

Results

multibody at 1 sec of simulation time

multibody at 4 sec of simulation time

multibody at 8 sec of simulation time

signal input vs multibody movement plot

force and velocity plot (prismatic joint)

referance

https://in.mathworks.com/help/simscape/ug/modeling-a-double-acting-actuator.html